Silly waveform question.

SolonOfAthens · Post by **SolonOfAthens** » Mon Dec 10, 2007 6:21 pm

I can't seem to find an answer for this on the net, so hopefully you guys can help me out. When I record vocals into Live or Logic the waveform that is displayed isn't always symmetrical above and below the "0" line. What does this mean? Is this normal? Does it depend on the polar pattern the mic being used? I noticed that when I turned my ribbon mic around that the uneven sides were swapped over the x-axis. My condenser with a cardioid pattern showed the same effect but it wasn't near as pronounced. I looked at some other vocals done by someone else and, although not perfectly symmetrical, they were pretty damn close to symmetrical. I know it's just a bunch of waves, but I thought the peak should somewhat match the bottom of the wave. Sorry for the ignorant question, but any insight would be greatly appreciated.

Tone Deft · Post by **Tone Deft** » Mon Dec 10, 2007 6:38 pm

google around for "zero offset".

it can happen with recordings, it's normal but not optimal. from what I know the biggest problem is that since the waveform is nudged upwards, when the end of the waveform plays you can get a popping sound from the sharp edge as the signal returns to zero.

interesting question, dunno if I can help any more than that. overall I wouldn't worry about it too much, you can ignore but addressing it isn't a bad idea if you have the time and interest.

laird · Post by **laird** » Mon Dec 10, 2007 6:43 pm

Not all waves are symmetrical.
for instance, a trumpet:

is obviously not symmetrical.

This is different from what ToneDeft mentions, where a waveform (symmetrical or not) is shifted so that it does not center on the zero mark.... a problem for headroom (this doesn't affect the sound) which can be fixed with "DC Offset"

Non-symmetrical waveforms can be natural.
They can also be the product of a type of distortion called rectification... such as in a Fuzz distortion pedal. You can't undo this distortion with DC offset.

SolonOfAthens · Post by **SolonOfAthens** » Tue Dec 11, 2007 12:20 am

Thanks for the help! I will google "zero offset." Also I've concluded that I must sing like a trumpet

I'll try the DC offset function too.
Thanks Y'all

Hedroom · Post by **Hedroom** » Tue Dec 11, 2007 1:01 am

Compression can make things look like this too.If you compress, say, a kickdrum with a fast attack, just the initial peak will come through at high amplitude. If this is very short then this could just be above (or below) zero.

SolonOfAthens · Post by **SolonOfAthens** » Tue Dec 11, 2007 5:10 am

Ok, I guess I really do sing like a trumpet (crappy). I've used both my DAW's, 3 different microphones. I've done a test for DC offset and there isn't any. So then I was worried that it was the new apogee duet that I bought, but when I recorded myself whistling the waveforms were nice and symmetric. The difference in peaks when I sing isn't terrible but there seems to be 5 to 15 points of difference usually in the negative region. I'm going to try it with my old audio interface this weekend and see if I have the same issue. Thanks again for all the tips.

SolonOfAthens · Post by **SolonOfAthens** » Tue Dec 11, 2007 6:03 am

Here we go!!! I found this quote in an online ProAudio Review article:
"Many voice waveforms (male in particular) exhibit quite a bit of asymmetry."

No wonder my whistles looked so nice